Different-end cooperation type energy absorption stand column combination structure on lower portion of aircraft fuselage floor
By introducing a shearing device and a fragment filling mechanism into the heterogeneous collaborative energy-absorbing column combination structure under the aircraft fuselage floor, the stress concentration and instability problems of composite material column structures are solved, achieving more efficient energy absorption and axial stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CIVIL AVIATION UNIV OF CHINA
- Filing Date
- 2023-04-07
- Publication Date
- 2026-05-08
AI Technical Summary
The existing cross-sectional composite material column structure under the fuselage floor of aircraft suffers from severe stress concentration at bolted connections, making it prone to local buckling, brittle fracture, and overall instability, and has insufficient energy absorption capacity.
The structure employs a heterogeneous collaborative energy-absorbing column combination structure. Through the built-in shearing device in the cap-shaped connection structure, the open-shear composite material column structure fails in a stable progressive shearing manner, enhancing axial stability. Progressive energy absorption is achieved through shear pin fracture and fragment filling.
It improves the local buckling and overall instability of the column structure during impact, enhances axial stability and energy absorption capacity, optimizes the force transmission path, and significantly improves the overall performance of the structure.
Smart Images
Figure CN121990152A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aircraft energy-absorbing structure technology, and in particular to a heterogeneous cooperative energy-absorbing column combination structure under the fuselage floor of an aircraft. Background Technology
[0002] Safety is an eternal theme, and aviation safety is a crucial component of national strategy and national security. Crash safety is an integral part of aviation safety. Aircraft accidents are always difficult to completely avoid, seriously threatening the lives of passengers and crew. To improve the survivability of occupants during emergency landings and prevent fatal injuries, a rational design must be adopted to reduce the impact overload transmitted to the occupants during an aircraft crash to within the limits of human tolerance. The subfloor support structure of the aircraft is the first to contact the ground, and its gradual failure absorbs a large amount of impact energy. The amount of energy absorbed directly affects the crash safety of the overall fuselage structure.
[0003] With the widespread application of composite materials in aircraft fuselage structures, cross-sectional column structures under the floor are also commonly made of composite materials, with C-shaped column elements being a typical example. Compared to closed composite column structures, cross-sectional composite column structures exhibit reduced energy absorption capacity. During crash impacts, their initial peak load is excessively high, and they are prone to overall buckling instability. Furthermore, cross-sectional composite column structures primarily rely on bolts at both ends for load transfer, leading to significant stress concentration at these connections. Existing fuselage frame crash tests and numerical simulations indicate that cross-sectional composite C-shaped column elements under the fuselage floor are susceptible to unstable failures such as localized buckling. Overall, these elements absorb relatively little energy, failing to maximize their energy absorption capacity. Therefore, it is essential to employ appropriate design to guide the progressive failure of cross-sectional composite C-shaped column elements, thereby enhancing their energy absorption capacity. Summary of the Invention
[0004] The purpose of this invention is to provide a heterogeneous cooperative energy-absorbing column assembly structure under the fuselage floor of an aircraft. This structure solves the problems of significant stress concentration at bolt holes in bolted composite material column structures, and the undesirable energy absorption mechanisms such as local buckling, brittle fracture, and overall instability that occur in sectioned composite material column structures during impact. The shearing device built into the cap-shaped connection structure allows the sectioned composite material column structure to fail in a stable, progressive shear manner, increasing its energy absorption during impact. The improved connection structure not only improves the traditional force transmission path but also increases the connection's effective range compared to traditional bolted connections, enhancing the axial stability of the sectioned composite material column structure and making it less prone to instability during impact.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention discloses a heterogeneous cooperative energy-absorbing column assembly structure for the lower part of an aircraft fuselage floor, comprising a lower floor beam, a lower floor cap-shaped connecting structure, C-shaped column elements, a fuselage frame cap-shaped connecting structure, and a fuselage frame. The lower floor cap-shaped connecting structure includes a lower floor beam connecting area and an upper connecting area for the C-shaped column elements. The lower floor beam connecting area is fixedly connected to the lower sidewall of the lower floor beam. The upper connecting area for the C-shaped column elements is fixedly connected to the upper end of the C-shaped column elements. The fuselage frame cap-shaped connecting structure includes a fuselage frame connecting area, a shearing device, and a lower connecting area for the C-shaped column elements. The fuselage frame connecting area is fixedly connected to the fuselage frame. The lower end of the C-shaped column elements is fitted into the lower connecting area of the C-shaped column elements and fixedly connected by shear pins. The shearing device... Located on the inner wall of the fuselage frame cap-shaped connecting structure, it is used to cut the lower end of the C-shaped column element under impact load. The structural strength of the lower floor cap-shaped connecting structure and the fuselage frame cap-shaped connecting structure is greater than the structural strength of the C-shaped column element. The C-shaped column element is a thin-walled hollow structure with an inner chamfer at the upper end. The contact area between the lower floor beam connection area of the fuselage floor and the upper connection area of the C-shaped column element is provided with a rounded corner guide arrangement. When subjected to impact load, the shear pin breaks, and the C-shaped column element contacts the shearing device. The shearing device cuts the lower end of the C-shaped column element into fragments. The fragments move upward along the internal cavity of the C-shaped column element and fill the internal cavity of the C-shaped column element under the guidance of the rounded corner guide arrangement and the inner chamfer.
[0006] Furthermore, the shearing device employs a sharp-angle cutting structure at one end edge near the C-shaped column element.
[0007] Furthermore, the fuselage frame cap-shaped connecting structure also includes a fragment release area and a fragment guide groove. The fragment guide groove is used to guide the cut fragments to move axially along the C-shaped column element, and the fragment release area is used to temporarily accommodate the fragments during the movement.
[0008] Furthermore, the lower floor beam connection area of the fuselage floor is a solid structure, and the upper connection area of the C-shaped column element is a thin-walled hollow structure that fits into the upper end of the C-shaped column element.
[0009] Furthermore, the fuselage frame connection area is a solid structure, and the lower end connection area of the C-shaped column element is a thin-walled hollow structure that fits into the lower end of the C-shaped column element.
[0010] Furthermore, the two C-shaped column elements are arranged symmetrically, and the placement angle of the two C-shaped column elements is in the range of 0-120°.
[0011] Furthermore, the C-shaped column element adopts a fiber-reinforced composite material structure.
[0012] Furthermore, the lower floor beam is fixedly connected to the lower floor beam connection area of the fuselage floor by bolts, and the fuselage frame connection area is fixedly connected to the fuselage frame by bolts.
[0013] Furthermore, the lower part of the fuselage frame and the long stringer are both fixedly connected to the fuselage skin.
[0014] Compared with the prior art, the beneficial technical effects of the present invention are as follows: During a survivable crash of a civil aircraft, the impact load is transferred through the bolted connections at the fuselage frame connection end to the cap-shaped connection structure in the fuselage frame connection area, and then uniformly applied to the composite C-shaped composite column through the cap-shaped connection structure. As the load increases, the shear pin breaks after reaching a threshold, and the C-shaped column element comes into contact with the shearing device and is cut into fragments. The fragments enter the fragment release area through the fragment guide groove and move upward along the internal cavity of the C-shaped column element. Finally, guided by the rounded corners and inner chamfers, they flip and fill the internal cavity of the C-shaped column element. This invention constructs a heterogeneous collaborative energy absorption mechanism of "lower-end cutting and upper-end guided inward flipping" by setting the cutting device on the inner wall of the lower cap-shaped connection structure and setting the inward flipping guide structure between the upper cap-shaped connection structure and the C-shaped column element. This allows the cut fragments to move a long distance along the inside of the column and then flip and fill inward, achieving orderly cohesion of the fragments and avoiding outward splashing of fragments that may interfere with or cause secondary damage to the surrounding structures such as the fuselage frame, stringers, and skin.
[0015] The heterogeneous cooperative energy-absorbing column assembly structure under the aircraft fuselage floor of this invention ensures that the structural strength of both the cap-shaped connection structure under the floor and the cap-shaped connection structure of the fuselage frame is greater than that of the C-shaped column element. This guarantees that failure occurs first and only at the C-shaped column element, while the connection structure remains intact. It provides a reliable guiding channel for the stable long-distance movement of debris, achieving controllability of the failure sequence. Simultaneously, the inner chamfer and rounded corner guidance arrangement at the upper end of the C-shaped column element, in conjunction with the rounded corners, allows upward-moving debris to orderly flip and fill the internal cavity of the column. The filled debris not only further absorbs impact energy but also enhances the column's later compressive strength through the filler material, achieving a synergistic effect of debris self-filling. This invention improves upon the existing floor support column structure of current civil aircraft by the same dimensions, making it easy to apply in engineering practice. It effectively improves the problems of local buckling, brittle fracture, and overall instability that are prone to occur during impact in the cross-section composite material column structure. It optimizes the force transmission path, increases the connection range, and strengthens the axial stability of the column, making it less prone to instability during impact, and significantly improves the overall performance and energy absorption capacity of the structure. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is a three-dimensional structural diagram of the heterogeneous cooperative energy-absorbing column combination structure under the aircraft fuselage floor of the present invention. Figure 2 This is a three-dimensional structural diagram of the column structure in the heterogeneous cooperative energy-absorbing column combination structure under the aircraft fuselage floor of the present invention. Figure 3 This is a three-dimensional structural diagram of the cap-shaped connection structure at the bottom of the floor in the heterogeneous cooperative energy-absorbing column combination structure at the bottom of the aircraft fuselage floor of the present invention. Figure 4 This is a three-dimensional structural diagram of the fuselage frame cap-shaped connection structure in the heterogeneous cooperative energy-absorbing column combination structure under the aircraft fuselage floor of the present invention. Figure 5 This is a schematic diagram of the internal three-dimensional structure of the fuselage frame cap-shaped connecting structure in the heterogeneous cooperative energy-absorbing column combination structure under the aircraft fuselage floor of the present invention. Figure 6 This is a three-dimensional schematic diagram of the internal side of the fuselage frame cap-shaped connection structure in the heterogeneous cooperative energy-absorbing column combination structure under the aircraft fuselage floor of the present invention. Figure 7 This is a three-dimensional structural diagram of the C-shaped column element in the heterogeneous cooperative energy-absorbing column assembly structure under the aircraft fuselage floor of the present invention. Figure 8 This is a partial three-dimensional structural diagram of the C-shaped column element in the heterogeneous cooperative energy-absorbing column assembly structure under the aircraft fuselage floor of the present invention.
[0018] Explanation of reference numerals in the attached drawings: 1. Lower floor beam; 2. Lower floor cap-shaped connection structure; 201. Lower floor beam connection area of the fuselage floor; 202. Upper connection area of the C-shaped column element; 3. C-shaped column element; 4. Fuselage frame cap-shaped connection structure; 401. Fuselage frame connection area; 402. Shear pin; 403. Debris release area; 404. Shearing device; 405. Debris guide groove; 406. Lower connection area of the C-shaped column element; 5. Fuselage frame; 6. Long stringer; 7. Fuselage skin; 8. Inner chamfer. Detailed Implementation
[0019] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0020] In the description of this invention, it should be understood that the terms "length," "width," "inner," "outer," etc., indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.
[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0022] The technical solutions provided by the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0023] like Figures 1 to 8As shown, the heterogeneous cooperative energy-absorbing column assembly structure under the aircraft fuselage floor of this embodiment includes a floor sub-beam 1. The lower sidewall of the floor sub-beam 1 is fixedly connected to the floor sub-cap-shaped connection structure 2 by bolts. The floor sub-cap-shaped connection structure 2 includes a fuselage floor sub-beam connection area 201 and an upper connection area 202 of the C-shaped column element. The upper connection area 202 of the C-shaped column element is fixedly connected to the upper end of the C-shaped column element 3. The lower end of the C-shaped column element 3 is provided with a fuselage frame cap-shaped connection structure 4. Specifically, the aircraft... The frame cap-shaped connection structure 4 includes a frame connection area 401, a shear pin 402, a debris release area 403, a shearing device 404, a debris guide groove 405, and a lower connection area 406 for the C-shaped column element 3. The lower end of the C-shaped column element 3 is fitted into the lower connection area 406 and fixedly connected by the shear pin 402. The frame connection area 401 is fixedly connected to the frame 5 by bolts. The lower part of the frame 5 and the stringer 6 are both fixedly connected to the frame skin 7. The shearing device 404 is set on the inner wall of the frame cap-shaped connection structure 4.
[0024] Preferably, the structural strength of the floor cap-shaped connection structure 2 and the fuselage frame cap-shaped connection structure 4 is greater than that of the C-shaped column element 3, so as to ensure that the C-shaped column element 3 collapses and absorbs energy before the floor cap-shaped connection structure 2 and the fuselage frame cap-shaped connection structure 4, thus avoiding the situation where the connection breaks prematurely and causes energy absorption failure.
[0025] Furthermore, a sharp-angle cutting structure is provided at one end edge of the shearing device 404 near the C-shaped column element 3. By providing the sharp-angle cutting structure, the sheared structural fragments are filled into the fragment release area, further enhancing the axial stability of the structure.
[0026] At this time, the placement angle of the two C-shaped column elements 3 is within the range of 0-120° and they are arranged symmetrically. This arrangement ensures that the force angle of the two C-shaped column elements 3 is as close as possible to the angle at the time of impact, so as to achieve gradual failure and absorb a large amount of energy.
[0027] The lower floor beam connection area 201 of the fuselage floor is a solid structure, while the upper connection area 202 of the C-shaped column element is a thin-walled hollow structure with the same inner layer as the C-shaped column element 3. The solid structure of the lower floor beam connection area 201 provides sufficient structural strength for the connection, while the thin-walled hollow structure of the upper connection area 202 of the C-shaped column element allows the C-shaped column element 3 to be fitted inside, thus collecting collapse debris and further improving the energy absorption effect.
[0028] In this embodiment, the fuselage frame connection area 401 is a solid structure, while the debris release area 403 and the lower connection area 406 of the C-shaped column element are thin-walled hollow structures with the same inner layer as the C-shaped column element 3. At this time, the solid structure of the fuselage frame connection area 401 provides sufficient structural strength for the connection, and the thin-walled hollow structure of the debris release area 403 and the lower connection area 406 of the C-shaped column element 3 allows the C-shaped column element 3 to fit inside, effectively collecting collapsed debris and further improving the energy absorption effect.
[0029] Furthermore, the C-type column element 3 adopts a fiber-reinforced composite material structure. Fiber-reinforced composite materials are materials composed of fibers and a matrix, possessing advantages such as high strength, high stiffness, low density, and corrosion resistance. They also exhibit lightweight, high strength, and high energy absorption, making them ideal materials for energy-absorbing columns. Their performance primarily depends on the type and content of the fibers; commonly used fibers include carbon fiber and glass fiber.
[0030] During a survivable crash of a civil aircraft, the impact load is transferred through the bolted connections of the fuselage frame connection area 401 to the cap-shaped connection structure 4 in the fuselage frame connection area, and then evenly applied to the composite C-shaped composite column through the cap-shaped connection structure. As the load increases, the force exerted by the lower part of the C-shaped column element 3 on the shear protection zone reaches a threshold, causing the shear pin to fail and break. The C-shaped column element 3 then comes into contact with the shear device 404 and is cut by the sharp-angle cutting structure. The cut composite C-shaped column element fragments enter the fragment release area 403 through the fragment guide groove 405. The cutting failure of the composite C-shaped column element further enhances the axial stability of the structure and guides the C-shaped column element 3 to undergo progressive failure, absorbing a large amount of energy.
[0031] Preferably, the C-shaped column element 3 adopts a thin-walled hollow structure, and an inner chamfer 8 is provided at one end of the upper connection area 202 of the C-shaped column element 3. Correspondingly, a rounded corner guide arrangement is provided in the contact area between the lower floor beam connection area 201 of the fuselage floor and the upper connection area 202 of the C-shaped column element.
[0032] During a survivable crash of a civil aircraft structure, the thin-walled hollow C-shaped column element 3 undergoes inward bending failure deformation due to the inner chamfer 8 at its upper end. The bent portion is continuously filled into the thin-walled hollow part of the C-shaped column element 3 by the rounded corners at the contact point between the C-shaped column element 3 and the cap-shaped connecting structure. The entire structure undergoes a progressive and effective energy absorption mode from bottom to top. Furthermore, the fragments of the broken lower structure continuously fill the interior of the thin-walled C-shaped column element 3 due to the design of the inner chamfer 8 structure, increasing the internal contact area of the thin-walled structure and further improving the structure's energy absorption capacity.
[0033] This invention improves upon the existing underfloor support structure of in-service civil aircraft by the same dimensions, making it easier to apply in engineering practice. Compared with the underfloor support structure already in use, it improves the problem of undesirable energy absorption methods such as local buckling, brittle fracture, and overall instability that are prone to occur during impact in composite material underfloor support structures, thus enhancing the overall performance and energy absorption capacity of the structure. The improved connection structure not only improves the traditional force transmission path but also increases the range of action of the connection compared to traditional bolt connections, strengthening the axial stability of the composite material support structure and making it less prone to instability during impact.
[0034] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. A composite structure of heterogeneous cooperative energy-absorbing columns under the fuselage floor of an aircraft, characterized in that, The system includes a lower floor beam (1), a lower floor cap-shaped connecting structure (2), C-shaped column elements (3), a fuselage frame cap-shaped connecting structure (4), and a fuselage frame (5). The lower floor cap-shaped connecting structure (2) includes a lower floor beam connecting area (201) and an upper connecting area (202) of the C-shaped column elements. The lower floor beam connecting area (201) is fixedly connected to the lower side wall of the lower floor beam (1), and the upper connecting area (202) of the C-shaped column elements is fixedly connected to the lower side wall of the lower floor beam (1). The upper end of the C-shaped column element (3) is fixedly connected. The fuselage frame cap-shaped connection structure (4) includes a fuselage frame connection area (401), a shearing device (404), and a lower end connection area (406) of the C-shaped column element. The fuselage frame connection area (401) is fixedly connected to the fuselage frame (5). The lower end of the C-shaped column element (3) is inserted into the lower end connection area (406) of the C-shaped column element and fixedly connected by a shearing pin (402). The shearing device (404) is provided with The inner wall of the fuselage frame cap-shaped connecting structure (4) is used to cut the lower end of the C-shaped column element (3) under impact load. The structural strength of the lower floor cap-shaped connecting structure (2) and the fuselage frame cap-shaped connecting structure (4) is greater than the structural strength of the C-shaped column element (3). The C-shaped column element (3) is a thin-walled hollow structure with an inner chamfer (8) at the upper end. The lower floor beam connection area (201) of the fuselage floor and the upper connection area (20) of the C-shaped column element are connected. 2) The contact area is provided with a rounded corner guide arrangement. When subjected to impact load, the shear pin (402) breaks, the C-shaped column element (3) contacts the shearing device (404), and the shearing device (404) cuts the lower end of the C-shaped column element (3) into fragments. The fragments move upward along the internal cavity of the C-shaped column element (3) and fill the internal cavity of the C-shaped column element (3) under the guidance of the rounded corner guide arrangement and the inner chamfer (8).
2. The heterogeneous cooperative energy-absorbing column assembly structure under the fuselage floor of an aircraft according to claim 1, characterized in that, The shearing device (404) has a sharp-angle cutting structure at one end edge near the C-shaped column element (3).
3. The heterogeneous cooperative energy-absorbing column assembly structure under the fuselage floor of an aircraft according to claim 1, characterized in that, The fuselage frame cap-shaped connecting structure (4) also includes a fragment release area (403) and a fragment guide groove (405). The fragment guide groove (405) is used to guide the cut fragments to move along the axial direction of the C-shaped column element (3). The fragment release area (403) is used to temporarily accommodate the fragments during the movement.
4. The heterogeneous cooperative energy-absorbing column assembly structure under the fuselage floor of an aircraft according to claim 1, characterized in that, The lower floor beam connection area (201) of the fuselage floor is a solid structure, and the upper connection area (202) of the C-shaped column element is a thin-walled hollow structure that fits into the upper end of the C-shaped column element (3).
5. The heterogeneous cooperative energy-absorbing column assembly structure under the fuselage floor of an aircraft according to claim 1, characterized in that, The fuselage frame connection area (401) is a solid structure, and the lower end connection area (406) of the C-shaped column element is a thin-walled hollow structure that fits into the lower end of the C-shaped column element (3).
6. The heterogeneous cooperative energy-absorbing column assembly structure under the fuselage floor of an aircraft according to claim 1, characterized in that, The two C-shaped column elements (3) are arranged symmetrically, and the placement angle of the two C-shaped column elements (3) is in the range of 0-120°.
7. The heterogeneous cooperative energy-absorbing column assembly structure under the fuselage floor of an aircraft according to claim 1, characterized in that, The C-shaped column element (3) adopts a fiber-reinforced composite material structure.
8. The heterogeneous cooperative energy-absorbing column assembly structure under the fuselage floor of an aircraft according to claim 1, characterized in that, The lower floor beam (1) is fixedly connected to the lower floor beam connection area (201) of the fuselage floor by bolts, and the fuselage frame connection area (401) is fixedly connected to the fuselage frame (5) by bolts.
9. A composite structure of heterogeneous cooperative energy-absorbing columns under the fuselage floor of an aircraft according to any one of claims 1-8, characterized in that, The lower part of the fuselage frame (5) and the long stringer (6) are both fixedly connected to the fuselage skin (7).